Process for sequestration of fluids in geological formations

Abstract

A process for geo-sequestration of a water-soluble fluid includes selection of a target water-laden geological formation bounded by an upper formation of low permeability, providing an injection well into the formation and injecting the fluid into the injection well under conditions of temperature, pressure and density contrast selected to cause the fluid to enter the formation and rise within the formation. This generates a density-driven convection current of formation water which promotes enhanced mixing of the water-soluble fluid with formation water.

1 . A process for sequestration of a water-soluble fluid within a subsurface water-laden formation, said process comprising:
 selecting a target water-laden geological formation;   providing a well bore of a fluid injection well into said formation, said well bore comprising at least one opening to discharge fluid into said formation;   providing a source of said fluid, said source in communication with said injection well;   injecting said fluid into said formation from said injection well under conditions of temperature or pressure, or both temperature and pressure, selected to cause said fluid to enter said formation and rise within said formation with sufficient volume, flow rate and density contrast between said fluid and water within said formation to induce a convection current of said fluid and water within said formation, said convection current sufficient to enhance convective mixing of said fluid and said water, relative to fluid injected under conditions which do not induce a convection current.   
     
     
         2 . The process of  claim 1 , wherein said injecting increases the rate of diffusive mass transfer or dissolution of said fluid into said water and flushes additional water substantially laterally into the region of said well bore, thereby increasing storage capacity and storage rate of said fluid in said formation. 
     
     
         3 . The process of  claim 1 , wherein said fluid comprises at least one water-soluble gas and at least one water-insoluble gas, said process further comprising:
 providing a withdrawal well in said formation; and   withdrawing said water-insoluble gas from said formation through said withdrawal well, thereby providing additional volume in said formation for further sequestration of said water-soluble gas.   
     
     
         4 . The process of  claim 3 , wherein said water-insoluble gas comprising the further step of passing said water-insoluble gas through a gas turbine after withdrawal thereof from said formation to generate electricity. 
     
     
         5 . The process of  claim 1 , further comprising:
 providing a water injection well into said formation; and   injecting water into said formation to produce a cross current of water within said formation from a region remote from said injection well and to further promote said convective mixing of said fluid with said formation water.   
     
     
         6 . The process of  claim 1 , further comprising providing a plurality of injection wells located within said formation for generating a plurality of convection currents within said formation. 
     
     
         7 . The process of  claim 1 , wherein said fluid is injected at a pressure below the fracture pressure of said formation. 
     
     
         8 . The process of  claim 1 , wherein said fluid is injected at a pressure above the fracture pressure of said formation. 
     
     
         9 . The process of  claim 1 , further comprising the step of injecting additional water into said formation to induce flux of fluid-unsaturated water into said formation in the region of said injection well. 
     
     
         10 . The process of  claim 1 , wherein said injection well is a substantially vertical injection well, a horizontal injection well or a deviated well. 
     
     
         11 . The process of  claim 1 , wherein said injection well defines a path for promoting said convective mixing in said formation. 
     
     
         12 . The process of  claim 1 , further comprising determining optimal placement of at least one opening in said injection well with respect to the configuration of said formation for improving said convection current, thereby further promoting enhanced mixing of said water-soluble fluid with said formation water. 
     
     
         13 . The process of  claim 1 , wherein said formation has an intrinsic permeability of at least 300 mD in the vertical direction. 
     
     
         14 . The process of  claim 1 , wherein said formation has a porosity exceeding 15% with the formation water being saline water. 
     
     
         15 . The process of  claim 1 , wherein one or more of the following parameters are assessed and/or manipulated individually or collectively to enhance said convective mixing of said fluid:
 a) composition of said fluid to be injected into said formation;   b) placement of said fluid injection well in said formation;   c) temperature of said fluid to be injected into said formation   d) rate of injection of said fluid into said formation;   e) injection pressure of said fluid into said formation;   f) numbers of said injection wells placed in said formation;   g) locations and profiles of said injection wells in said formation;   h) pH of said water in said formation;   i) salinity of said water in said formation;   j) density of said water in said formation;   k) volume of said injected fluid;   l) partial pressure of said injected fluid in said formation water; and   m) density of said fluid.   
     
     
         16 . The process of  claim 1 , wherein said fluid comprises flue gas. 
     
     
         17 . The process of  claim 16 , further comprising enriching the concentration of carbon dioxide within said flue gas prior to injection into said formation. 
     
     
         18 . The process of  claim 1  wherein said fluid comprises one or more gases selected from the following group: carbon dioxide, nitrogen, methane, NOM, and hydrogen sulfide. 
     
     
         19 . A process for determining conditions for sequestration of a water-soluble fluid within a water-laden formation comprising:
 providing a computer programmed with a computer program stored on a computer readable medium, said program comprising a representation of a known geological formation and at least one injection well for injecting a mixture of soluble and insoluble fluid into said formation, said computer program provided with means to vary one or more parameters selected from the group consisting of:   a) composition of said fluid to be injected into said formation;   b) placement of said fluid injection well in said formation;   c) temperature of said fluid to be injected into said formation   d) rate of injection of said fluid into said formation;   e) injection pressure of said fluid into said formation;   f) numbers of said injection wells placed in said formation;   g) locations and profiles of said injection wells in said formation;   h) pH of said water in said formation;   i) salinity of said water in said formation;   j) density of said water in said formation;   k) volume of said injected fluid;   l) partial pressure of said injected fluid in said formation water; and   m) density of said fluid;   wherein said computer program is configured to calculate properties of a convection cell generated in said formation arising from density-driven movement of said fluid and formation water within said formation influenced by one or more of said parameters;   inputting into said computer some or all of said parameters a through m; and producing a report providing sequestration conditions and preferred injection conditions comprising said one or more parameters.   
     
     
         20 . The process of  claim 19 , wherein said computer program is further provided with means to vary placement of one or more fluid withdrawal wells in said formation. 
     
     
         21 . The process of either of  claim 19 , wherein said computer program is further provided with means to vary placement of one or more water injection wells in said formation. 
     
     
         22 . A process for sequestration of a water-soluble fluid within a water-laden formation comprising:
 providing a computer programmed with a computer program stored on a computer readable medium, said program comprising a representation of a known geological formation, and at least one fluid injection well, said computer program provided with means to vary one or more parameters selected from the group consisting of:   a) composition of said fluid to be injected into said formation;   b) placement of said fluid injection well in said formation;   c) temperature of said fluid to be injected into said formation   d) rate of injection of said fluid into said formation;   e) injection pressure of said fluid into said formation;   f) numbers of said injection wells placed in said formation;   g) locations and profiles of said injection wells in said formation;   h) pH of said water in said formation;   i) salinity of said water in said formation;   j) density of said water in said formation;   k) volume of said injected fluid;   l) partial pressure of said injected fluid in said formation water; and   m) density of said fluid;   wherein said computer program is configured to calculate properties of a convection cell generated in said formation based on dispersion of fluids in said formation, said dispersion of fluids influenced by said one or more parameters;   inputting into said computer some or all of said parameters a through m;   manipulating said one or more parameters to generate an effective convection cell;   replicating said one or more parameters with components of an injection well system at the site of said formation and thereby generating at least one density-driven convection current within said formation; and   sequestering said water-soluble fluid using said injection well system.   
     
     
         23 . The process of  claim 22 , wherein said computer program is further provided with means to vary placement of a plurality of fluid injection wells in said formation. 
     
     
         24 . The process of  claim 22 , wherein said computer program is further provided with means to vary placement of one or more fluid withdrawal wells in said formation. 
     
     
         25 . The process of  claim 22 , wherein said computer program is further provided with means to vary placement of one or more water injection wells in said formation. 
     
     
         26 . The process of  claim 1 , wherein said water-soluble fluid comprises a gas that is not in a supercritical form. 
     
     
         27 . The process of  claim 1 , wherein said water-soluble fluid comprises a gas that is in a supercritical form.